The earth is 4.6 billion years old. We humans have lived on the earth for only 35 000 years, but during this period, we have changed our planet a lot in many ways.  

All over the world, people have cut down millions of trees.  Forests have become deserts, so many kinds of animals and plants are disappearing.

Factories have also polluted the land and the water.

Around the earth, there's a special kind of oxygen called "ozone" (O₃). But now air pollution is destroying it and making a very big hole in the ozone layer.

It mainly comes from burning oil, coal and wood. This has formed a blanket around the earth. The heat from the sun can't escape so the temperature is rising. It causes the level of the oceans to rise and the climate of the earth to change.

All these problems are very serious, so we must do something now.
 

When people talk about air pollution, they are usually thinking about outdoor air1. But do you know that there is also air pollution inside homes, offices, hotels and other buildings? The air in your home can be 2 to 100 times more polluted than the air outdoors! In fact, some American doctors say that 50% of the illnesses have2to do with the polluted indoor air.

A lot of pollution comes from indoor activities3smoking and cooking. As most people 4about 80%-90% of their time inside buildings, it is important to take indoor air pollution seriously, too.

Air pollution influences our health5. When the air is polluted, not only young children and old people6from it,7people with health problems suffer as well. Indoor air pollution can8people's eyes, noses and throats. Air pollution, both indoor and outdoor, can also9to lung cancer and heart disease! In the great London fog in 1952, 4, 000 people died in a few days10the pollution! It is said that half a million young children and women die each year in India because of indoor air pollution!